How to find the coordinates of the turning points of a curve on a graph

The turning point of a curve occurs when the gradient of the line = 0The differential equation (dy/dx) equals the gradient of a line. Therefore in this case the differential equation will equal 0.dy/dx = 0Let's work through an example. If the equation of a line = y =x² +2xTherefore the differential equation will equaldy/dx = 2x +2therefore because dy/dx = 0 at the turning point then2x+2 = 0Therefore:2x+2 = 02x= -2x=-1 This is the x- coordinate of the turning pointYou can then sub this into the main equation (y=x²+2x) to find the y-coordinate. So if x = -1:y = (-1)²+2(-1)y = (1) +( - 2)y = 3This is the y-coordinate of the turning pointTherefore the coordinates of the turning point are x=-1, y =3= (-1,3)